How to build a boot.img file

VIM3
#1

我从github单独clone u-boot文件夹：
$ git clone git://github.com/khadas/u-boot.git -b khadas-vims-pie --depth 1

编译得到的是u-boot.bin
$ ./mk kvim3l

在u-boot CLI下需要的是boot.img。如何得到?
usb_update boot boot.img

或者如何烧录u-boot.bin到eMMC中？

#2

kvim3l#usb_update bootloader u-boot.bin
usb_start_count 0
(Re)start USB…
USB0: USB3.0 XHCI init start
Register 3000140 NbrPorts 2
Starting the controller
USB XHCI 1.10
scanning bus 0 for devices… 3 USB Device(s) found
scanning usb for storage devices… init_part() 282: PART_TYPE_DOS
1 Storage Device(s) found
[fat]Filesize is 0x18ad70B[1M]
[MSG]Down(store) part(bootloader) sz(0x18ad70) fmt(normal)
[MSG]totalSlotNum = 0, nextWriteBackSlot 25
[fat]Filesize is 0x18ad70B[1M]
[fat]0x:leftSz d70 < BPS 1000, gotSz ad70
[MSG]Burn Start…
Wrting blocks 1 to 3159 @ user
Wrting blocks 1 to 3159 @ boot0
boot_info.rsv_base_addr : 12000
boot_info.ddr.addr : 4000
boot_info.ddr.size : 0004
boot_info.version : 0001
boot_info.checksum : 16005
Wrting blocks 1 to 3159 @ boot1
boot_info.rsv_base_addr : 12000
boot_info.ddr.addr : 4000
boot_info.ddr.size : 0004
boot_info.version : 0001
boot_info.checksum : 16005
[MSG]Burn complete
BURN u-boot.bin to part bootloader OK!
=====>Burn part bootloader in fmt normal OK<======

kvim3l#